In a bowl, whisk the eggs, sea salt and black pepper. Set aside.

In 6 muffin cups, evenly divide the bell pepper, sausage, and kale. Fill each cup with the egg mixture. Arrange the muffin pan in a 4- to 6-quart slow cooker. Cover and cook on LOW for 2 hours or until the egg muffins are cooked through.

Alternatively, for an egg casserole: grease the slow cooker pot with olive oil. Pour the egg mixture into the slow cooker. Top with the bell peppers, sausage, and kale. Cover and cook on LOW for 5 to 6 hours, or until the eggs are set.